Battery grid

ABSTRACT

A battery grid includes a frame that includes a top element, a bottom element, a first side element, and a second side element. The battery grid also includes a plurality of wires provided within the frame and defining a plurality of open areas and a current collection lug extending from the top element in a first direction. The battery grid further includes at least one feature provided in the battery grid that is configured to reduce the amount of growth of the battery grid in the first direction due to corrosion of the battery grid during the life of the battery grid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority as a continuation application of U.S.application Ser. No. 12/823,803, now U.S. Pat. No. 7,955,737, filed Jun.25, 2010, which is a continuation application of U.S. application Ser.No. 11/984,666, now U.S. Pat. No. 7,767,347, filed Nov. 20, 2007, whichis a national stage application of International Application No.PCT/US2006/019686, which has an international filing date of May 22,2006, which claims the benefit of U.S. Provisional Patent ApplicationNo. 60/683,608, filed May 23, 2005, the entire content of which ishereby incorporated by reference herein.

BACKGROUND

The present inventions relate to grids for use in batteries (e.g.,lead-acid batteries such as batteries for vehicle starting, lighting,and ignition applications; marine batteries; commercial batteries;industrial batteries; batteries for use with hybrid-electric vehicles;etc.). More specifically, the present inventions relate to grids thathave a configuration which resists shorting of a battery cell due togrowth of the grids.

Lead-acid batteries conventionally include a number of cells in whichenergy is stored. For example, a 12 volt battery may include six cells,each of which provides 2 volts. Each of the cells includes one or morepositive electrodes or plates and one or more negative electrodes orplates. An electrolyte (e.g., acid such as dilute sulfuric acid) is alsoprovided in the cells to facilitate chemical reactions which take placein the cells during charging and discharging of the battery.

The positive and negative electrodes each comprise a grid made from leador a lead alloy (e.g., a lead-calcium alloy) on which an active materialin the form of a paste is provided. Such grids include a plurality ofwires coupled to a plurality of nodes (e.g., a battery grid may includea frame comprising four sides with a lug or current collector extendingfrom one of the sides and a network of wires or grid elementsinterconnected with a plurality of nodes).

The positive and negative electrodes are arranged in each of the cellsin alternating fashion and are separated from adjacent plates by aseparator (e.g., a microporous polymeric separator). For example, thenegative electrodes may be contained within a separator envelope toelectrically isolate them from adjacent positive electrodes. In thismanner, the positive and negative electrodes are prevented from cominginto direct contact with each other, which would cause a short in thecell.

Over an extended period of use, the grids will corrode, which in turnwill cause the grids to grow. By way of illustration, FIG. 1 shows acell having a first electrode 10 (e.g., a positive electrode) with acurrent collector 12 arranged adjacent a second electrode (e.g., anegative electrode, partially obscured by electrode 10 in FIG. 1) with acurrent collector 22. The current collector 12 of the positive electrodeis electrically coupled to other positive electrodes in the cell by astrap or connector 14, while the current collector of the negativeelectrode is electrically coupled to other negative electrodes in thecell by a strap or connector 24. The positive strap in a cell is thenconnected to a negative strap in the next cell.

Growth of positive electrode 10 is illustrated by dashed lines 30 and32. When installed in a battery container, the grids are generallyconstrained on their sides and bottom by walls of the battery container.Accordingly, growth of the grids generally occurs along the top surfaceof the grids. In certain situations, such unconstrained growth in thepositive vertical direction may cause a short of the cell. For example,as shown in FIG. 1, the growth of the positive grid illustrated bydashed line 32 results in a portion of the grid coming into contact withstrap 24 that is connected to the negative electrodes. In such asituation, the positive and negative electrodes are electrically coupledtogether, which may act to short the cell. Thus, while adjacent positiveand negative electrodes may be separated from each other with apolymeric separator, shorting may still occur due to corrosion of thegrids which causes growth in the vertical direction.

While it is known to provide grids for use in batteries, such known gridconfigurations do not provide certain advantageous features and/orcombinations of features.

SUMMARY

An embodiment of the present invention relates to a battery grid thatincludes a frame that includes a top element, a bottom element, a firstside element, and a second side element. The battery grid also includesa plurality of wires provided within the frame and defining a pluralityof open areas and a current collection lug extending from the topelement in a first direction. The battery grid further includes at leastone feature provided in the battery grid that is configured to reducethe amount of growth of the battery grid in the first direction due tocorrosion of the battery grid during the life of the battery grid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the growth of a battery grid due to corrosion whichmay result in shorting of a battery cell.

FIG. 2 is a plan view of a battery grid according to an exemplaryembodiment.

FIG. 3 is a plan view of a portion of a battery grid similar to thatshown in FIG. 2 that includes a modified configuration that is intendedto restrain the overall growth of the grid due to corrosion.

FIG. 4 is a plan view of a portion of a battery grid similar to thatshown in FIG. 2 that includes a modified configuration that is intendedto restrain the overall growth of the grid due to corrosion.

FIG. 5 is a plan view of a portion of a battery grid similar to thatshown in FIG. 2 that includes a modified configuration that is intendedto restrain the overall growth of the grid due to corrosion.

FIG. 6 is a plan view of a portion of a battery grid similar to thatshown in FIG. 2 that includes a modified configuration that is intendedto restrain the overall growth of the grid due to corrosion.

FIG. 7A is a plan view of a portion of a battery grid similar to thatshown in FIG. 2 that includes a modified configuration that is intendedto restrain the overall growth of the grid due to corrosion.

FIG. 7B is a plan view of a portion of a battery grid similar to thatshown in FIG. 2 that includes a modified configuration that is intendedto restrain the overall growth of the grid due to corrosion.

FIG. 8 is a plan view of a portion of a battery grid similar to thatshown in FIG. 2 that includes a modified configuration that is intendedto restrain the overall growth of the grid due to corrosion.

FIG. 9 is a plan view of a portion of a battery grid similar to thatshown in FIG. 2 that includes a modified configuration that is intendedto restrain the overall growth of the grid due to corrosion.

DETAILED DESCRIPTION

FIG. 2 illustrates a battery grid 100 according to an exemplaryembodiment. Grid 100 may be either a positive or a negative grid, andmay be produced by any known method (e.g., by casting, by expansion of asheet of material after piercing the sheet, by a progressive punchingoperation, etc.) using any known materials (e.g., lead or lead alloys,such as lead-calcium alloys, etc.). Various nonexclusive examples ofbattery grids that may be used in accordance with the present disclosureare shown, for example, in the following U.S. Patents, the disclosuresof which are hereby incorporated by reference: U.S. Pat. No. 5,582,936;U.S. Pat. No. 5,989,749; U.S. Pat. No. 6,203,948; U.S. Pat. No.6,245,462; and U.S. Pat. No. 6,274,274.

Referring to FIG. 2, grid 100 comprises a frame that includes a topframe element 112, first and second side frame elements 114 and 116, anda bottom frame element 118. The grid 100 includes a series of grid wiresthat define open areas 120 that hold electrochemically active paste (notshown) that provides the current generation for a battery. A currentcollector or lug 122 is integral with the top frame element 112 and isoffset from the center of the top frame element 112. The top frameelement 112 includes an enlarged conductive section 124 directly beneaththe lug 122, and has the shape shown to optimize current conduction tothe lug 122.

A series of radially extending vertical grid wire elements 126 form partof the grid 100. The vertical wire elements 126 are connected to the topframe element 112 and at least one of the bottom frame element 118, thefirst side frame element 114, and the second side frame element 116. Thevertical wire elements 126 become closer together when moving from thebottom element 118 towards the top element 112 and get farther apartwhen moving towards the left element 114 or the right element 116.

The grid 100 also includes a plurality of horizontal or cross wireelements 130. Individual sections of the vertical wire elements 126 andthe horizontal wire elements 130 ends which are joined at a plurality ofnodes 144 that define the open areas 120 that support theelectrochemically active paste for conduction.

FIGS. 3-9 illustrate various modifications to the grid shown in FIG. 1that are intended to retard, restrict, or restrain growth of the grid100 when the grid 100 corrodes during its useful life in a battery. Thecircled numbers shown in FIG. 2 reflect the location on the grid 100where the various modifications are to be made (e.g., the modificationshown in FIG. 3 is designated by the circled number 3 in FIG. 2).

As shown in FIG. 3, a “weak link” may be provided for one of thehorizontal or vertical wire elements. For example, according to anexemplary embodiment, a first portion or segment 220 of a wire 200 maybe joined to a second portion or segment 230 of the wire 200 by aportion or segment 210 that is configured to break when a thresholdamount of stress is applied to the wire 200. When growth of the grid 100causes movement of the first portion 220 relative to the second portion230, the middle portion 210 will break, which may act to interrupt thegrowth of the grid at this point. As shown in FIG. 3, middle portion 210is provided to connect portion 220 to portion 230 such that portion 220is “staggered” relative to portion 230. According to various exemplaryembodiments, any suitable number of weak links may be provided in thegrid to redirect the stresses caused by growth of the grid due tocorrosion, and they may be provided for both vertical and horizontalwires as may be desired.

As shown in FIG. 4, one or more of the vertical and horizontal wires maybe configured to act as a fuse that is intended to break when athreshold amount of stress is applied or to corrode away at a given timeof the battery life. According to an exemplary embodiment shown in FIG.4, a wire 300 may include a first portion or segment 320 and a secondportion or segment 330 connected by a relatively thin portion or segment310 (e.g., portion 310 has a smaller cross-sectional area and/or adifferent cross-sectional shape as compared to the remainder of wire300). When growth of the grid occurs as a result of corrosion, a tensilestress may be applied to the wire 310. Because the portion 310 has asmaller cross-sectional area than that of portions 320 and 330, the wire300 will break in the portion 310 if a sufficient degree of stress isapplied or will corrode away. Such breakage may act to interrupt thegrowth of the grid at this point. According to various exemplaryembodiments, any suitable number of horizontal or vertical wires may beprovided in the grid as may be desired, and any of a variety ofconfigurations may be provided for the fuse.

As shown in FIG. 5, a distortion may be provided in one or more of thewires that is intended to absorb or redirect a portion of the stressresulting from the growth of the grid. According to an exemplaryembodiment shown in FIG. 5, a rounded feature 410 may be provided in awire 400. When the grid experiences growth due to corrosion, the shapeof the wire 400 may be altered. The inclusion of a distortion (e.g.,rounded portion 410) may deflect some of the growth (e.g., by providingsomething other than a straight line for growth). In this manner, thegrowth of the grid may be interrupted at this point. According tovarious exemplary embodiments, any suitable number of vertical orhorizontal wires having distortions may be provided in the grid, and anyof a variety of configurations may be used for the one or moredistortions.

As shown in FIG. 6, a portion of one of the frame elements may include anotch or cutout. According to an exemplary embodiment as shown in FIG.6, the bottom frame element 118 may include a notch or cutout 119 thatis intended to act as a point of weakness for the frame. When stressesare introduced which result from growth of the grid, the stress may beconcentrated at the point of weakness such that the frame breaks at thispoint. In this manner, the growth of the grid may be interrupted, andthe stresses may be redirected within the grid. It should be noted thatwhile notch 119 is shown as extending inward from the outside of frameelement 118, according to other exemplary embodiments, the notch mayextend from the inside of the frame element. According to variousexemplary embodiments, any suitable number of notches or cutouts may beprovided at various locations along the sides, top, and/or bottom of theframe.

As shown in FIG. 7A, one of the frame elements may include an indent ordepression. For example, according to an exemplary embodiment shown inFIG. 7A, the top frame element 112 of the grid 100 includes an indent113. The top frame element 112 is effectively bent at this point. Whenthe grid 100 grows in the vertical direction due to corrosion, theindent 113 is pushed upward due to accumulated stresses in the grid.Because the top frame element 112 includes an indent, it will take alonger period of time for the grid to extend upwards to make contactwith, for example, a strap connected to grids of opposite polarity. Thatis, because the top frame element at the point of the indent is notcollinear with the rest of the top frame element, growth of the gridwill first cause the grid to grow toward the rest of the top frameelement; only after this point would the grid continue to grow in thevertical direction. According to various exemplary embodiments, anysuitable number of indents may be provided at various locations alongthe sides, top, and/or bottom of the frame.

As shown in FIG. 7B, a portion of the top frame element may be arrangedat an angle to the rest of the top frame element. For example, as shownin FIG. 7B, a portion 115 of the top frame element 112 is slanted orangled (e.g., sloped, tapered, etc.) downward. Similar to the indentdescribed with respect to FIG. 7A, the slanted configuration of the topframe element 112 acts to extend the amount of time that the grid mustgrow in order to contact a strap of opposite polarity. Such aconfiguration may also act to increase tension in the grid, which mayact to counter some of the grid growth.

As shown in FIG. 8, one or more of the corners of the grid may beprovided with a rounded shape. For example, according to an exemplaryembodiment shown in FIG. 8, a rounded corner 117 is provided whichconnects the top frame element 112 to the side frame element 114. Suchrounded shape may act to redirect the stress and change the direction ofthe grid growth away from the vertical direction.

As shown in FIG. 9, various wires may be removed to form an engineeredbuffer zone within the grid (similar to a “crumple zone”). In aconventional grid (e.g., such as that shown in FIG. 1), vertical wiremembers are collinear with each other and extend, for example, from thetop frame element to the bottom frame element. As a result, growth ofone of the vertical wires is translated to others which are collinear,resulting in an additive growth effect that acts to force the top frameelement toward a strap of opposite polarity (as shown, for example, inFIG. 1). According to the exemplary embodiment as shown in FIG. 9, oneor more of the vertical wires are removed such that there is aninterruption or discontinuity in the grid (e.g., wires 154 and 156 areseparated by an open space 152). The open space 152 thus acts as abuffer zone into which the vertical wires may grow (instead oftranslating their growth in a manner which results in movement of thetop frame element of the grid). The open space 152 thus acts to “absorb”the growth in the vertical direction. Any number of engineered bufferzones may be provided at various desired points within the grid.

It should be noted that while the above-described modifications to thegrid have been discussed individually, any one or more of suchmodifications may be utilized in a single grid. For example, both a“weak link” (as shown, e.g., in FIG. 3) and a “distortion” (as shown,e.g., in FIG. 5) may be provided in a single grid. Any other combinationof modifications such as those described above may also be utilized inorder to manage the growth of the grid.

In operation of a battery using a grid such as that described herein,corrosion of the battery grid material (lead or a lead alloy) will causegrowth of the battery grid. Because the grid is constrained at itsbottom and sides by the walls of the battery container, growth isdirected in the vertical direction toward the top of the grid. Byintroducing modifications to the grid which are intended to shunt orredirect the growth of the grid, the life of the battery may beextended. For example, by introducing weak points in the grid that areintended to break once a threshold amount of stress is reached, growthmay be interrupted or redirected at such points to reduce the growth ofthe grid in the vertical direction. Any of a variety of modificationsmay be made to the grid in order to manage the growth of the grid andextend the life of the battery by reducing the occurrence of shortswhich result from portions of the grid contacting features electricallycoupled to features in the battery having an opposite polarity.

Those reviewing this disclosure will appreciate that various advantagesmay be obtained using the grid designs described herein. For example,according to an exemplary embodiment, the battery grid provides desiredperformance characteristics while resists shorting due to grid growth.The battery grid includes features which are intended to act to retard,restrain or restrict growth of the grid due to corrosion. According toan exemplary embodiment, the battery grid includes one or moremodifications that are intended to absorb or redirect stresses that mayresult from growth of the grid (e.g., due to corrosion of the grid). Itis intended that such grid designs provide the battery grid, and hencethe battery in which it is provided, with an enhanced useful life ascompared to conventional battery grids.

It is important to note that the construct on and arrangement of thebattery grid as shown in the various embodiments is illustrative only.Although only a few embodiments of the present inventions have beendescribed in detail in this disclosure, those skilled in the art whoreview this disclosure will readily appreciate that many modificationsare possible (e.g., variations in sizes, dimensions, structures, shapesand proportions of the various elements, values of parameters, mountingarrangements, use of materials, orientations, etc.) without materiallydeparting from the novel teachings and advantages of the subject matterrecited in the claims. Accordingly, all such modifications are intendedto be included within the scope of the present invention as defined inthe appended claims. Other substitutions, modifications, changes andomissions may be made in the design, operating conditions andarrangement of the preferred and other exemplary embodiments withoutdeparting from the scope of the present inventions.

What is claimed is:
 1. A battery grid comprising: a frame comprising atop element, a bottom element, a first side element, and a second sideelement; a plurality of wires provided within the frame and defining aplurality of open areas, including a plurality of first linear verticalwire members which radially extend from the top element to the bottomelement, a plurality of second linear vertical wire members which extendfrom the bottom element toward the top element but terminate beforereaching the top element creating a subset of open areas, and aplurality of linear horizontal wire members which extend between thefirst side element and second side element, wherein a portion of theplurality of wires includes at least one of the second linear verticalwire members provided between consecutive first linear vertical wiremembers, each of the second linear vertical wire members contact aplurality of linear horizontal wire members prior to termination,wherein the subset of open areas is asymmetric across the grid; and acurrent collection lug extending from the top element in a firstdirection.
 2. The battery grid of claim 1, wherein the battery gridcomprises at least one rounded corner between the top element and atleast one of the first and second side elements that redirects forcesdue to growth of the grid from the first direction toward a seconddirection.
 3. The battery grid of claim 1, wherein the top element meetsone of the first or second side elements at an angle such that at leasta portion of the top element is not perpendicular to at least one of thefirst and second side elements.
 4. The battery grid of claim 3, whereinthe angle between the top element and at least one of the first andsecond side elements is greater than ninety degrees.
 5. The battery gridof claim 1, wherein a plurality of horizontal wire members interconnectthe first side element and the second side element.
 6. The battery gridof claim 1, wherein the plurality of horizontal wire members include afirst horizontal wire member which contiguously extends from the firstside element or the second side element, and a second horizontal wiremember which contiguously extends from the first side element or thesecond side element, the plurality of linear vertical wire membersintersects the first and second horizontal wire members.
 7. The batterygrid of claim 1, wherein: the portion of the plurality of wires is afirst portion of the plurality of wires; and the plurality of wiresinclude a plurality of third linear vertical wire members which extendfrom the top element toward the bottom element but terminate beforereaching the bottom element, wherein a second portion of the pluralityof wires include one of the plurality of third linear vertical wiremembers provided between consecutive first linear vertical wire members,each of the third wire members contact a plurality of horizontal wiremembers prior to termination.
 8. The battery grid of claim 7, whereinthe plurality of first linear vertical wire members intersect a firstplurality of the plurality of horizontal wire members, the plurality ofsecond linear vertical wire members intersect a second plurality of theplurality of horizontal wire members, and the plurality of third linearvertical wire members intersect a third plurality of the plurality ofhorizontal wire members.
 9. The battery grid of claim 1, wherein theplurality of first linear vertical wire members intersect a firstplurality of the plurality of horizontal wire members, and the pluralityof second linear vertical wire members intersect a second plurality ofthe plurality of horizontal wire members.
 10. A battery grid comprising:a frame comprising a top element, a bottom element, a first sideelement, and a second side element; a plurality of wires provided withinthe frame and defining a plurality of open areas, the plurality of wiresinclude a plurality of linear first wire members which radially extendfrom the top element to the bottom element, a plurality of linear secondwire members which extend between the first side element and second sideelement, and a plurality of linear third wire members which extend fromthe bottom element toward the top element but without intersecting thetop element creating a subset of open areas, wherein the first and thirdwire members contact a plurality of linear second wire members, andwherein at least one linear third wire member is provided betweensuccessive linear first wire members wherein the subset of open areas isasymmetrically distributed across the grid; and a current collection lugextending from the top element.
 11. The battery grid of claim 10,wherein the battery grid comprises at least one rounded corner betweenthe top element and at least one of the first and second side elements.12. The battery grid of claim 10, wherein the top element meets one ofthe first or second side elements at an angle such that at least aportion of the top element is not perpendicular to at least one of thefirst and second side elements.
 13. The battery grid of claim 12,wherein the angle between the top element and at least one of the firstand second side elements is greater than ninety degrees.
 14. The batterygrid of claim 10, wherein the plurality of second wire membersinterconnect the first side element and the second side element.
 15. Thebattery grid of claim 10, wherein the plurality of linear first wiremembers intersect at least two of the second wire members.
 16. Thebattery grid of claim 10, wherein: the plurality of wires includes aplurality of fourth linear wire members, the fourth linear wire membersextend from the top element toward the bottom element, contacting aplurality of horizontal wire members but without intersecting the bottomelement, wherein a second portion of the plurality of wires includes oneof the plurality of fourth linear wire members being provided betweensuccessive linear first wire members.
 17. A battery grid comprising: aframe defined by a top element, a bottom element, and opposing first andsecond side elements; a current collection lug connected to the topelement; a plurality of wire elements provided within the frame anddefining a plurality of open spaces, the plurality of wire elementsinclude first linear vertical wire members extending from the topelement to the bottom element, second linear vertical wire membersextending from the bottom element toward the top element but terminatingbefore intersecting the top element creating a subset of open spaces,and linear horizontal wire members extending between the first andsecond side elements, wherein the first and second linear wire memberseach contact a plurality of linear horizontal wire members, and a firstportion of the plurality of wire elements includes a plurality of secondlinear vertical wire members provided between successive first linearvertical wire members, the subset of open spaces thereby beingasymmetrically distributed about the grid.
 18. The battery grid of claim17, wherein the first linear vertical wire members radially extend fromthe top element.
 19. The battery grid of claim 17, wherein the pluralityof wire elements include third linear vertical wire members extendingfrom the top element toward the bottom element but terminating beforeintersecting the bottom element, wherein a second portion of theplurality of wire elements includes at least one of the third linearvertical wire members provided between successive first linear verticalwire members.
 20. The battery grid of claim 19, wherein the first linearvertical wire members intersect a first plurality of horizontal wiremembers, the second linear vertical wire members intersect a secondplurality of the horizontal wire members, and the third linear verticalwire members intersect a third plurality of the horizontal wire members.